Circuit breaker



Mj' 9, 1944. v v. M. sc-o'rr, JR

CIRCUITA BREAKER FiledJune l0, 1940 9 shams-sheet 1 INVENTOR.

lll

F ICS I ATTORNEYS May 9, 1944.' w. M. scQTn JR CIRCUIT BREAKER' f FiledJune l0, 1940 9 Sheets-Sheet 2 F' I C5. 2. I l zxfENroR.

BY Jua/mrd@ SwCC ATTORNEYS 9 sheets-sheet s" w. M. SCOTT, JR

CIRCUIT BREAKER -Filed June 1o,` 1940 'eo a@ -AnjroRNEYs www, mwll May9, m44 W. M. scoTT, JR 2,348,22

C IRCUIT BREAKER May 9, 1944 w. M SCOTT, JR .52,348,22@

CIRCUIT BREAKER Filed June lO, 1940 9 Sheets-Sheet 5 u l l INVENTOR.

May 9 m44- w. M. SCOTT, m

C IRCUI T BREAKER Filed June lO, 1940 9 Sheets-Sheet 6 1N VENT OR.

ATTORNEYS May 9, 1944o w. M. scm-T, .m

CIRCUIT BREAKER Filed June lO, 1940 9 Sheets-Sheet 7 FEGS.

May 9, 1944. W, M. S'COTT, JR 2,348,228

CIRCUIT BREAKER Filed June l0,- 1940 9 Sheets-Sheet 8 Y A EL l N VENTOR.

mj W ATTORNEYS May 9, 1944. W* M SCOTT, 1R 2,348,228

CIRCUIT BREAKER Filed June l0, 1940 9 Sheets-Sheet 9 INVENTOR.

WMM/WA ATTORNEYS Patented May 9, 1944 CIRCUIT BREAKER William MaxwellScott, Jr., Bryn Mawr, Pa., as-

sign

or to I. T. E. Circuit Breaker Company,

Philadelphia, Pa., a corporation of Pennsylvania Application June 10,1940, Serial No. 339,687

(Cl. 20G- 144) 4 Claims.

This invention relates to circuit breakers and operating mechanismthereof including contact structures, magnetic blow-out devices, arcquenchers and closing and tripping mechanisms, and to the integration ofall of these elements into a single unit for composite operation.

In the operation of circuit breakers, the eiciency of togglearrangements for effecting tripping and closing of the contact membershas long been recognized and has been employed in various combinationswith different types of latching and tripping arrangements.

An important element of the present invention is to provide inconnection with a toggle closing mechanism novel means whereby themovable contacts may be operated either manually or electrically inorder to effect the closing operation; and correspondingly novel meanswhereby either a manual operation or an automatic electrically inducedoperation may selectively effect the tripping of the mechanism and thefast opening of the contacts.

An important element of toggle mechanisms is the latch or other engagingmeans which holds the same in predetermined locked position and whichshould be so designed as to obviate slipping during closing or anyresponse to the jar of the solenoid or any other vibration, while at thesame time being required for tripping.

In the present invention the problem is solved not by the use of asingle latch or trip alone but by a combination of latches; primarily bywhat we have termed a primary latch held in position by a secondarylatch and engaging as well the tip of a latch lever This apparentmultiplication of latches does not, as might at rst be suspected,increase the complexity of the mechanism but rather simplifies theoperation and makes it possible to provide for an automatic resetting ofthe latches immediately after the actual tripping operation. Inthereafter reclosing the circuit breaker the only operation necessary isthe actual movement of the contact by the toggle means herein described.

An object of thisv invention, therefore, is, in a circuit breakerclosing mechanism of the toggle type, the provision of a primary latchfor engaging a suitable latch lever of the toggle mechanism and asecondary latch for maintaining the primary latch in latching position.

A second and equally important object of the present invention is thenovel arrangement of the latch lever, the primary latch and thesecondary latch in such a manner that the very process of tripping thecontacts open sets the members in such position that the latches areautomatically reset immediately after the tripping operation iscompleted. y

It thus becomes important that the cooperation between the two latchesin the first instance and between the primary latch and the latch leverbe such that some movement of a portion of the toggle mechanism relativeto these members have a resultant force effective to reengage thesemembers while at the same time in no way impeding the trippingoperation.

Accordingly, a further important object of the invention is theprovision of means whereby relatively slight motions result in theinitiation of the tripping operation and'whereby the tripping operationitself results in the resetting of the engaging means or latches.

Two desirable features of a circuit breaker are first, the contactsshould open in the shortest possible time, and, second the Work demandedof the automatic tripping device in releasing the latch should be aminimum. In order to have a circuit breaker open quickly, it isnecessary to provide spring powerful enough to give the requiredacceleration. The opening force of the springs and the contact pressureis transmitted through the mechanism to the latch surface when thecircuit breaker is closed. In order to use powerful springs and yet havea small pressure .on the latch surface, it is necessary to providerelatively great mechanical advantage. The simplest form of mechanicaladvantage is to use a lever of considerable length, the force involvedbeing applied to this lever and the end of the lever; restrained by thelatch. The greater mechanicaladvantage required, the longer this Ileverwill be, the latch engaging the end farthest from the fulcrum. Inproviding mechanical advantage in this form the length of leverintroduces a mass and increases the moment of inertia of the mechanismlThis mass must be accelerated during opening and such a constructionwould materially delay the opening of the contacts. It is, therefore,desirable to design a mechanism giving the required mechanical advantageand yet introducing the minimum inertia in the parts. This was theguiding element in producing the design of the'present invention.

In the present invention it was found that it was not necessary to use alarge mechanical advantage in the parts effecting the closing of thecontacts, but it was necessary to introduce a large degree of mechanicaladvantage as far as the latches were concerned. Therefore, two latcheswere used in series, one latch restraining the other. The primary ofthese latches is designed to resist a high percentage of opening forceof the contact mechanism and to be able to automatically release upondisengagement of the secondary latch. This primary latch was made withthe most economical use of material to make it light, the metal being intension and the area of engagement being relatively wide and yet havingrelatively small overlap so that a very short movement of the latch willdisengage it from the closing mechanism.

The secondary latch engages the primary latch to maintain it in theholding position and the mechanical advantage produced by this systemgives a very light load on the secondary latch. 'Ihe secondary latchcan, therefore, be released with a very small amount of energy.

In connection with circuit breaker mechanism it is found extremelydesirable to have the restraining latches engaged before the closingmovement commences, and to have the latching members stationary duringthis movement.

In certain earlier circuit breaker designs an actuated lever was heldtogether by means of a latch so that during closing the two levers movedtogether, being maintained in their relative positions by the engagementof the latch. Due to 4 centrifugal force or shock or other influencesduring the closing operation, it was very easy for these latches tobecome disengaged when this action was not desired. In the presentinvention the latches are engaged immediately after the opening of thecontacts and remain stationary throughout subsequent closing so thatthere are no outside secondary forces introduced which might cause themto slip.

We have therefore arranged a latch lever in connection with the togglemechanism in such a manner that when the contacts are closed and thetoggle mechanism is under collapsing pressure by reason of a spring orother means, the latch lever exerts a pressure upon that portion of theprimary latch which engages it.

We also provide that this pressure upon the primary latch be in adirection so that if the primary latch were permitted to yield to it,there -would be a disengagement of the latch lever and the primarylatch. In order temporarily to prevent this yielding of the primarylatch, we provide a secondary latch which is subject only to thepressure generated by the tendency of the primary latch to move or yieldout of position.

The manual or electrical tripping means need, therefore, merelydisengage the secondary latch, whereupon the primary latch may yield tothe existing pressure upon it by the latch lever and permit thedisengagement of the latch lever and the resultant instability of thetoggles will return the mechanism to its original position, thus openingthe contacts.

Upon release of the secondary latch, the primary latch is moved to asecond position under the force exerted by the latch lever upon theholding force oi' the primary latch. In this second position, theholding surface is moved from engagement with the latch lever whichlatter moves to open circuit position under the influence of the circuitbreaker opening springs, During this movement a surface of the latchlever maintains engagement with the primary latch so that the latter ismaintained in its second position. In this second position the primaryengages the secondary latch to prevent its returning to engagedposition.

We further provide a means on the primary latch and an arrangement ofthe latch lever with the toggle mechanism so that as the toggles returnto their original position, the latch lever no longer exerts a pressurein the original direction which caused the yielding vof the primarylatch but is caused to exert a pressure in the opposite directioncausing it to rise up and engage another portion of the primary latch,reset it. and engage the latching portion thereof.

When the primary latch is thus withdrawn from its yielded position tothe original engaged position, nothing prevents the return of thesecondary latch to its original engaged position and a simple spring maybe utilized for this latter purpose.

An important object of the present invention. therefore, is thearrangement of a latch lever, a primary latch and a secondary latch sothat when the circuit breaker is closed, a force is exerted by the latchlever upon the primary latch in one direction and so that immediatelysubsequent to the tripping operation, the force is exerted by the samelatch lever in an opposite direction in order to reset all of thelatches.

'Ihe tripping mechanism and the arrangement thereof is fully set forthin the following specification and drawings and other objects and usesand arrangements thereof will be more clearly understood therefrom.

In cooperation with this type oi toggle mechanism and particularly inorder to cooperate with a type of toggle mechanism where a plurality oftoggles are used and wherein none of the knuckles or knee pins of thetoggles pass through center and where, therefore, a locking action isnot obtained by means of the inherent nature of the toggle itself but bymeans of abutments or latches, it becomes important that the contactsthemselves be so arranged that they may be effectively locked inposition when they are in the closed circuit relation.

Accordingly, an important object of the present invention is themounting of the main contacts not directly lupon the contact arm itselfbut upon an auxiliary contact lever which has an independent fulcrum ofits own upon the contact arm and which by means of a compression springoperating not directly upon the contact end of the lever but upon theopposite end of the contact lever tending to raise it, tends to increasethe pressure between the moving contact and a stationary contact.

This principle may be applied as well to the arcing contact which may bemounted upon the main contact arm but also is not mounted directlythereon but is mounted upon an auxiliary arcing contact lever which hasits fulcrum upon the main contact arm and which by means of acompression spring is held in close engagement with the stationaryarcing contact.

In this manner and by this arrangement of auxiliary levers uponthe mainlever and by the further arrangement of the compression springs inconnection with the auxiliary levers, the fact that knee pins orknuckles of the various toggles do not pass through center to effect anormal locking action of the average toggle is compensated.

In this manner also the toggles are left unstable and biased towardsopening position rather than towards closed position so that in theevent of any disengagement of any of the members by reason of anyoperating difficulty of any kind, the tendency of the toggles will be toforce the ycontacts open rather than to force them into tighterarrangement with each other (as would be the case in a mechanism wherethe toggles were required to pass through center in order to effect theclosing operation).

A positive abutment must therefore be utilized in connection with thetoggle mechanism in order to hold the knee pin thereof in positionagainst the tension of the toggle spring when the contacts are closed.The operation of the latches hereinbefore described operates also toremove the abutment from the supporting position and thus permits thecircuit breaker to open. This arrangement is nevertheless such thatshould any difficulty occur in operation, the toggle mechanism is (evenin closed position) biased towards opening so 'that the contacts wouldtend to open.

However, where a circuit breaker of this type is to be used underconditions subject to mechanical shocks and stresses as, for instance,in naval vessels of various types, it becomes important that themechanical shocks to which such vessels and the equipment thereof aresubject in normal operation as well as during actual manoeuvering andtiring operations be not permitted to result in the accidental openingof circuit breakers and the resultant temporaryeessation of operation ofimportant apparatus.

Accordingly, the positive abutment herein described for support of thetoggle mechanisms in their unstable positions is of more practical usethan any over-center arrangement which may by some mischance be vibratedthrough center and toward opening position. The tripping operation isnot interfered with since in such arrangement we contemplate themovement of the abutment out of supporting position by the latch lever.

In circuit breakers of this type wherein toggle mechanisms are permittedto rapidly open the contacts and wherein substantial currents maynevertheless ow, arcing across the contacts as they open and even afterthey may be opened presents a serious problem. The main contact may beprotected by an arrangement wherein the arcing contact is caused to openan instant after the main contact so that whatever arc is establishedwould tend to pass between the arcing contacts. The arcing contacts ma;Tbe made readily replaceable and of relatively inexpensive materials.

The protection of the main contacts therefore insures that when thecontacts are re-engaged once more in closed circuit position, thecurrent may flow freely therebetween without undue heating.-

is a further protection, however, a magnetic blow out coil may beprovided and the stationary arcing contact may actually be mounted onorimmediately over the coil to bring the arc more closely under theinuence of the magnetic blow out means. The movable arcing contact as itopens may come into arcing relation with a stationary arcing horn towhich the arc may be transferred. r

Stationary magnetizable plates on either side of the contacts may engagethe core of the blow out coil so that the magnetic eld may extend in apredetermined manner substantially through the entire space occupied bythe arc and thus cause the arc to move in a predetermined direction inaccordance with the current flow.

The magnetizable plates may be magnetized not merely by their contactwith the core of the magnetic blow out coil; but the arc itself.'whileit is in existence, may itself constitute virtuallyv a half turn coilwhich energiges the magnetic blow out plates and results in a movementof the arc along the arcing horns in a predetermined direction.

An important object, therefore. of the present invention is to soarrange a magnetic blow out coil and magnetizable blow out plates inproximity to the position of the arc and to the arcing horns so that themagnetic uxes generated by the magnetic blow out coil as well as by thecurrent of the arc itself may cause the arc to move in a predetermineddirection away from its original position. A

The arrangement of the arcing horns so that they separate in thedirection in which the arc is forced to move serves further to attenuatethe arc.

And nnally in this path of movement of the arc, we inter-pose an arcquenching device consisting preferably of plates of fibrous materialbetween which the ionized gases forming the arc are squeezed and broughtinto contact with cooling and de-ionizing surfaces which serve todeionize the gases to extinguish the arc.

An important object of the present invention, therefore, is thearrangement of an arc quencher having a series of parallel fiber platesso arranged that the are may be forced longitudinally between them fordie-ionization of the gases and the extinguishment of the arc.

In the operation of circuit breakers and switch gear of various types,particularly where such mechanisms control the operation of a motor, ithas frequently been found that the operator thereof will attempt to incha motor into starting by just touching the contacts together and openingthem slightly, and then attempting to close them once more. Suchoperations have well known dangerous possibilities which need not herebe enumerated, the important element being that it is essential inordinary operation that some provision be made for preventing suchattempts which may lead to destruction of the circuit breaker or of themotor which it controls or which may in more ordinary cases lead to morerapid deterioration of the contacts.

Accordingly, an object oi this invention is to provide primarily inconnetcion with the toggle closing mechanism a back up trip which willserve automatically to trip the circuit breaker open as soon as any evenslight reverse movement occurs during the closing operation.

In the operation and use of circuit breairers and switch gear of varioustypes, it often becomes important to disassemble the same or at least toremove partsthereof in order to obtain access to various portions of thecircuit breaker for replacement or repair. We have attempted inthepresent invention to so arrange each of the parts that they may bereadily removable without any complicated operations whatever.

Thus the entire arc quencher assembly including the magnetic pole piecesof the blow out coil may be removed after rotating a single screw. Theentire contact assembly may be removed after having simply removed thetwo outer bearings of the contact shaft and the single pin connectingthe contactshaft with the toggle mechanism and removing the flexibleconductors from the lower terminal. And even here the link loetween thetoggle mechanism and the contact shaft is hinged sufficiently to permitthe entire contact assembly to be rotated outwardly to permit inspectionand repair thereof.

Access to principal leads and attachment thereof in operative positionis provided for by means of a single screw and the entire toggle andlatching mechanism is contained within a housing which may readily beremoved by the rotation of the screws attaching it to the shelf.

An important object, therefore, of the present invention is thearrangement and integration of the parts thereof in such a manner as tofacilitate assembly and disassembly thereof in manufacture, operation,replacement and repair.

In the operation and use of an integrated unit of this type, it becomesextremely important to provide and integrate with such a unit varioussafety factors which will tend towards fool-proof operation.

Accordingly, it is an important object of the present invention toprovide a means for locking the circuit breaker in tripped position sothat no unauthorized operator may effect a closing thereof and it is apreferred object that said locking means be in. connection with or evena part of the manual tripping means so that any person attemptinganunauthorized closing will be aware that the means has been set toprevent such closing. Such locking device precludes both manual andelectrical operation.

Other objects of the present invention comprise the provision ofsuitable signalling devices and means integrated and connected with thevarious parts of the circuit breaker mechanism for indicating therelative position of each of the members-thereof.

'I'here are many other objects and uses of the present invention and ofthe combinations and elements herein set forth. Many of them .havealready been pointed out. Many others will in part be apparent and wherenot intrinsically apparent will be pointed out in the followingdescription and drawings, in which:

Figure 1 is a side elevation of the circuit breaker of our invention.

Figure 2 is a iront view of the circuit breaker arrangement of Figure 1.

Figure 3 is a cross-sectional view on line 3 3 of Figure 2 showing thecircuit breaker in closed circuit position.

Figure 4 is a view corresponding to that of Figure 3 showing the circuitbreaker in open circuit position.

Figure 5 s's a cross-sectional view on line 5-5 of Figure 4 showing thearrangement of the arc quencher.

Figure 6 is a top view taken on line 6--6 of Figure 4 of the togglemechanism for closing and opening the circuit breaker.

Figure 7 is a horizontal cross sectional view taken on line 1-1 ofFigure 10 showing the arrangement of the parts of the members of Figure6.at a different horizontal level within the toggle mechanism container.

Figure 8 is a cross-sectional view partly in elevation taken on line 8-8of Figure 9.

Figure 9 is a cross-sectional view partly in elevation taken online 9 9of Figure 6 showing the position of the members when the contacts areopen.

Figure 10 corresponds to Figure 9 but shows the position of the memberswhen the contacts are closed. i

Figure 11 corresponds to Figure 8 and is a cross-sectional view on lineIi--II of Figure 10,

y :,asaans also showing a position of the closing operation.

Figure 12 is a cross-sectional view on line I2-I 2 of Figure 9.

ligure 13 is a schematic view in perspectiv of the toggle and latchmechanisms of Figures 6. '1, 9 and 10 when the contacts are closed.

Figure 14 is a schematic view in perspective corresponding to theconstruction of Figure 13 but showing the toggle mechanisms during oneinstant of the tripping operation.

Figures 15 and 16 are schematic views in perspective showing the back-uptrip mechanism and manual trip mechanismsy and the combination thereofwith the latching mechanisms ,of the members of Figures 6. 7. 9 and 10.

members during a Figure 17 is a view of the back of the contact vsupporting shaft showing the back of the contact arms.

Figure 18 is a cross-sectional view on line Il il of Figure 17.

Figure 19 is a schematic view in perspective illustrating the on-on'indicator and the operation thereof.

Figure 20 is a cross-section of the contact assembly of Figure 18 takenalong line 2li- 20.

Figure 21 is a view in perspective showing the contact surfaces.

Figures 22, 23, 24 and 25 are diagrammatic representations of varioussteps in the operation of the toggle mechanism.

Figure 26 is a cross-sectional view on line 28-29 of Figure 18.

Referring now to Figures 1, 2, 3 and 4, w have here shown a three pole'circuit breaker comprising the elements of the present invention. Thecircuit breaker consists of a group of pole units 20, 2|, 22 (Figure 2)mounted on the face of an ebony, asbestos or slate panel 23 which formsthe mounting plate of the entire circuit breaker arrangement.`

Main supporting members The main bracket or housing 24 which supportsthe operating members is secured to the panel 23 by means of screws 25,25 the heads of which are recessed in openings 26, 26 in the back of thepanel 23 and which pass through the perforations 21, 21 in said panel toengage the main bracket 24 (Figure 1)..

As seen in Figures 1 and 2, the main bracket or housing preferablycomprises two flanged side plates 28 and 29 which extend on each side ofa horizontal shelf 30 to which they are welded. The operating mechanism3| comprising the toggles and other elements hereinafter described isbolted to the lower side of the shelf 30, the housing 390 of the saidoperating mechanism comprising flanges 32, Figures 3 and 4, through:hhich bolts 33 may be passed to engage the shelf Link 34 of insulatingmaterial connects the operating mechanism 3i to the lever 35 which issecured to the contact shaft 45 and is rotatable therewith. As seen moreparticularly in Figures 3 and 4,A the stationary contacts 36 and theirback connection stud assembly are mounted on the panel above the housingor supporting bracket 24 and support the inner end of the arc chutes inthe manner hereinafter described.

A bridge I1 of insulating material secured to the outer end of the mainbracket 24 supports the outer end of the arc chutes in the mannerhereinafter described.

lain and arcing contacts-The stationary main contacts current when thecontacts are closed, as seen in Figure 3, is through the connection stud42, the stationary contact 35. the stationary contact tip 45, themovablecontact tip 4I, the contact lever 55 carrying the flexible connection 43which in turn is electrically connected to the member 44.

Movable contacts support The movable contact shaft 45 is preferably asquare steel bar coveredwith phenolic insulation molded in place and isrotatably supported in appropriate bearings as hereinafter described.

A contact arm for each pole is mounted on this shaft. The contact arm 45is preferably a bronze casting reinforced by flanges 41 and 45. Thelower end of the bronze casting which engages the square steel shaft ispreferably formed in a V comprising the members 49 and 50 set atapproximately right angles to each other so that they will engage thesquare sides of the shaft 45 to which they are to be clamped.

The clamping member comprises also a V- shaped member having the sides52 and 53 which likewise may engage the sides of the square steel shaftand comprising also flanges 54 and 55 through which bolts 55 ancl 51 maybe threaded to engage the flange 55 and the at portion 59 of the contactarm 55 in order to securely clamp the same to the contact shaft 45.

As will be noted, especially in connection with Figures 2 and 3,-each ofthe main contact arms 46 may be secured to the contact shaft 45 so thatrotation of the contact shaft 45 by the lever 35 will result incorresponding movement of the contact arms 45 for the purpose of openingor closing the circuit.

vWhile any necessary number of contact carrying arms may b'e mountedupon the contact shaft as the specific circuit connections may requireonly one lever 35 is necessary for the opening and closing operationswhich result in rotation of the haft 45 and the operation of the variousconacts.

In order to obtain a balanced structure it is preferred that the lever35 be secured to the shaft substantially at the center so that themechanism may be properly balanced.

Movable main contacts Each contact arm 45 carries a pair of contactlevers 50 formed and cut from a special copper extruded bar. Each ofthese two levers 60 (see especially Figures 3 and 4; see also Figure 17)carries at its upper end a silver nickel contact block 4I for engagingthe stationary main contact tip 40. The back of the contact arm i5 has apart-cylindrical depressioh 8l and the front of each of the contactlevers has a similar depression 62. A bronze pivot pin 53 is placed inthese depressions (in the manner shown in Figures 3, 17 and 21). Thispivot pin has flanges at each side and also a flange in the centerbetween the two contact levers 50 in order to prevent any lateralmovement of the members with respect to each other.

Each of the contact levers 50 is drilled at 55 so that a pin -65 may beinserted therein. The

pin 551s preferably of dumbell shape (as seen in Figure 26) and acts asan equalizing yoke between the two contacts ill-50. A link 55 engagesthe pin 55 between the two contact levers 55-55 and is extended upthrough a perforation 51 in the contact arm 45 into the recessed area 58of said contact arm. A compression spring 58 forms the main contactspring and is retained in position between the base of the recess 58 andthe spring cup 10 which is held in place on the spring link 55 by thecotter pin 1 i The spring link '55 in extending between the two maincontact levers 50 has an eye 55' engages a groove 55 in the pin l55 inorder to prevent its moving to either side. l

When the main contacts are disengaged in the manner shown in Figure 4,Athe lower ends 12 of the main contact levers 50 press aaginst thecontact arm 45 in the manner shown.

For simplified assembly the only Oelement which retains the pin 53 inplace is the pressure of the spring 59 upon the main contact lever.

In the closedposition the pressure through the contact lever 50 betweenthe spring 69 (bearing on the pin 55) and the contact 4I serves tomaintain the adequate pressure necessary to hold the pin -53 in place.In the open position, the pressure of the bottom end 12 of the maincontact lever 55 against the contact arm 45 and the pull of thecompression spring upon the pin' 55 of the lever 50 using the mem-ber 12as a fulcrum serves to maintain the pin 53 in place.

This design of pivot provides long wearing surfaces. The spring link andpressure equalizing pin may be made of hard steel so that their area ofengagement may be small. 'I'he area of engagement at the pin of thecontact levers may vbe of relatively soft material.

The pivot pin engaged by the half cylindrical surfaces of the contactarm and the contact levers provides a maximum of area for the softerparts. same width of pin length by any other method.

If the levers were formed to rock in a groove in the arm, there would becopper and brass bearing surfaces which are far inferior to the steelpin between them.

During the closing movement there is no instant when there is anyrelaxation of pressure upon the pin 63, for until the main movingcontact tip il is brought into contact with the stationary contact tip45, the bottom end 'l2 of the contact lever 5l) engages the contact armt5 in the manner shown in Figure 4.

Only after the moving contact tip 4l is in engagement with thestationary contact tip il@ is there a transfer of the fulcrum or thebase of pressure from the portion 12 to the tip M. such case, as hasbeen seen in connection with the closed position of Figure 3, there isagain sufficient pressure to maintain the pin 53 in place.

During the opening movement, pressure is maintained upon the pin B3 byreason of the fact that spring 59 Aby its pressure on pin forcescontacts 4) and M against each other until, in the rotation of thecontact shaft 45, the end 12 of the contact lever presses againstclamping portion #it of the contact arm bili, whereupon the base ofpressure is transferred from contact tip M to end portion 12. In thismanner, the spring pressure is always exerted to maintain pin 53 inposition.

The rotation of the main contact lever 5@ about the pin 52 during theclosing operation This area could not be obtained in the necessarilyresults in a slight sliding motion of the movable contact tip 4i withrespect to the stationary contact tip 40 so that a wiping action occurstending to clean the contacts.

As seen also in Figures 3 and 4, the back of the contact levers Varedrilled and tapped for the securing screws 13 in order to attach theflexible conductor 43 thereto.

The upper end of the flexible conductor 43 is slit so that separatescrews 13 may attach the separate ends to the two separate contactmembers 6!) to allow independent movement of the contacts. 'I'hearrangement of the lever arms above and below the contact pivot is suchthat during heavy current iiow the magnetic forces set up will tend toincrease the pressure between the moving and stationary contacts whenthe ilow of current is between the stationary contact tip 49 and themovable contact tip 4 I.

By the use of two contact levers of this type for each pole of thecircuit breaker, an adequate contact at each pole is ensured.

Movable arcing contacts The arcing contacts 81 are mounted in the upperpart of the contact arm 4B, and are supported by arcing contact levers15. The arcing contact levers 15 preferably are each cut from a bar ofextruded copper and in this -case also I have found it preferable to usea pair of such contacts and levers for a single pole. Each of the4arcing contact levers 15 is pivoted on the pin 16 which is grocvedbetween the contacts to take a hair pin spring 11 which serves to keepthe pin 16 in center position. A second pin 1B is mounted in the top ofthe contact arm 46 between two upwardly extending anges 19 thereof.

An appropriate bushing may be placed between the flanges so that the pinmay be securely riveted over them without bending them. The eye 80 ofthe spring link 8| is placed over the bushing, the said spring link 3|extending beyond the back of the arcing contact levers 15.

Pins 82 having rounded heads (see Figure 18 as well as Figures 3 and 4)are driven into the upper part of the back of the arcing contact lever15.

A spring cup 83 is pressed against these pins by the compression spring84 which is held in place on the link 8| by the spring cup 85 at theopposite end which in turn is held in position by the cotter pin 36. Thearcing contact 81 is mounted upon the arcing contact lever 15 and ispreferably formed or cut from an extruded copper bar and is providedwith a contact face 39 preferably of Elkonite silver which is solderedto r the copper.

Each of the contacts 81 of each of the contact levers 15 is held inplace upon its contact lever by a socket head cap screw 89 and lockwasher 90. As willcbe seen more particularlyv in Figure 18, the contacts81 are held against turning or other displacements by the shoulder 9|which engages a corner of the arcing contact lever 15. 'I'he ends of thecontact arm flanges bear against the outer sides o1' the two arcingcontacts and the projection 92 oi' the spring link separates the twoarcing contacts 81-81 from each other, thus serving adequately toposition them.

As is seen in Figures 3, 4 (and 18), the lower end of the arcing contactlever 15 is oiI-set at 93 to receive vthe end of -a flexible conductor93. The conductor 93 like the conductor 4I is also slit,

the ends thereof being riveted at the oil-set 93' 75 to the arcingcontact lever 15 by means of the rivet 94 passing through the washerplate 94,

The off-set 93 is curved away at 96 from the ilexible conductor and thewasher plate 95 is curved away 'at 91theretrom for the purpose ofpreventing kinking during operation. This flexible conductor 93 is leddown to the lower terminal block 44 to which it is connected by the samescrews 98 that hold the main contact lead The main contact levers, incontact open position, are held against their fulcrums and against astop on the arm by a compression spring at the back of the arm, actingon a link connected to the two contact levers between the fulcrum andthe stop. The contact surface is at the top of the lever above thefulcrum. The flexible conductor is secured to the bottom of the leverbelow the fulcrum.

When the shaft and arm are moved to contact closed position, the contactends of the levers are rotated about their fulcrums and pushed back fromtheir advanced position, moving the bottom stop clear of the arm. Thiscompresses the spring and increases the contact pressure. The use of asingle spring and link between the two levers permits the pin to act asan equalizing yoke.

The attachment of the flexible conductor below the fulcrum causes themagnetic forces to balance about the fulcrum so that the contactpressure may remain the same or increase during fault current.

The auxiliary or moving arcing contacts are mounted at the top of thearm. In this case the spring is above the fulcrum and below thedetachable contact tips. Equalization of pressure is arranged in thesame way. Maintained pressure during fault or inrush current is providedin the same manner.

Overcurrent coil connections It should also be noted that the flexiblelead |00 from the arcing horn hereinafter described is also connected tothe terminal block 44. It will thus be seen that the three iiexibleconductors |00, 93 and 43 are al1 led from the contact structure to thelower terminal 44 to which al1 three are or may be secured by the samescrews and lock washers. The angle of the terminal and of the screw 98is selected so that a repair man may reach these screws over the backedge of the bracket shelf 30.

The lower terminal or pigtail posts may have connected thereto a coil H0which may energize an over-current magnet.

This coil may have a. cross-section of copper and the requisite numberof turns corresponding to the current rating of the circuit breaker, oneterminal of the coil being connected to the lower terminal post 44 andthe opposite end of the coil being connected to the back connection studIII which has thesecuring block H2 welded to it at the face of the panel23.

The back connection stud III is held in place in the panel 23 by thescrews H3 and H4 which pass through and engage the clip IIS. Theterminal post 44 is bolted in place on the panel 23 by means of thebolts IIB and lock washers H1. In vother words, therefore., the currentis not led directly to the back connection stud III but through thelower terminal post 44 and through the coil H0 oi' the over currentmagnet to the back connection stud I I I through which the connection ismade to the circuit.

assenso The coi1 ||0 of the over current magnet is therefore connectedin series with the contacts.

It might here be noted that the upper back connection stud 42 islikewise connected through the panel 23 by means of screws ||0 and ||3engaging and passing through the clip |20 and is therefore held inposition in the same manner as the lower back connection stud the directpressure of the terminal |25 against the connection stud 42.

when the circuit breaker therefore is c1osed.`""'- opened, with thearcing contacts; and, finally,

with the arcing horns; since the leads 43, 93 and each are connected tothe pigtail post 44.

The arcing contact circuit is in parallel with the circuit through themain contact tips 40 and 4|. The` arcing contacts are designed to makebefore and separate after the main contacts during the closing andopening so that as is hereinbefore described, the arc particularlyduring the opening may be made between the arcing contacts so that themain contacts which carry the load should not be roughened or distortedto offer any substantial resistance to the passage of current.

Blow out mag-net and stationary arcing contact The current path from thearcing contact tip 88 to the arcing contact lever 15 and through theflexible lead 93 to the lower terminal block 44 has been described. Themovable arcing contact tip 88 engages the stationary arcing contact tip|2|. Current is led to the stationary arcing contact tip |2| in thefollowing manner:

Current from the upper connection stud 42 flows into the lower terminal|25 of the blow out magnet coil |22 around the coil to its upperterminal |29 and thence to the stationary arcing contact |23. tact, thecurrent flows to the' stationary arcingcontact tip |2|, thence to themovable arcing contact tip 38, thence through the arcing con tact leverl5, flexible lead 93, the terminal block 44, the coil H0, and theconnection stud ii in the manner hereinbefore described. The arcingcontacts, particularly the movable arcing tips ill-88, may readily bereplaced after the same have become worn. When the circuit breaker isclosed, the resistance of the circuit through the main contacts 36 and`liti is low as compared with the resistance through the arcing circuitso that a relatively small current ows through the latter.

The main stationary contact 36 is attached to the back connection studas is the lower terminal of the blow-out magnet coil |22 by means ofscrews 38. Screws ||9 passing through panel 23 serve to fasten the lowerterminal of blow out magnet coil |22 and angle clip |20 to panel. ScrewsH8 in turn fasten back connection stud 42 to the angle clip |20. Theelectrical connec tion between the back connection stud 42 and the lowerterminal |25 of the blow out magnet coil |22 is made by direct contactbetween the lliv From the stationary arcing conangle clip |20 and thescrew ||9 as well as by 75 The coll consists preferably of v a strip ofbar copper wound 'in ahelix, the lower end at |23 being sweated andpinned by pins |21 and |23 to the lower coil terminal |25 and the upperend being secured to a nat plate-terminal |29 which lies against .thepanel |23. The coi1 is wound so that current flowing from the lowerbcoil terminal to the upper coil terminal flows around the slottedcylindrical iron core |30 in a clockwise direction in the views ofFigures 3- and 4.

A fiber tube |3| insulates the` core |30 from the coil |22. Insulatedside plates |32 are fastened on each side of the coil terminals. Thearcing terminal |23 also cut from an extruded brass bar is secured tothe upper coil terminal |29 and the panel 23 `by screws |33, threadedinto the nut plate |34 which is further anchored in position to providea secure attachment of the members by the screws |35, the heads of whichare embedded in the recess |36 so that they may not interfere with thesecurement of the coil terminal |29 to the panel.

The upper part |38 of the arcing contact |23 is extended along the paneland forms a hook |39 for anchoring the arc chute in the mannerhereinafter described.

The .arcing'contact |23 curves around the blow out coil as seen inFigures 3 and 4 and forms an arcing horn. The arcing contact ispreferably wider than the coil |22 and as seen in Figures 3 and 4, itsunder surface rests against the edges of the insulating side plates |32.As has been above described, the arcing contact tip |2| is at the lowerend of the arcing contact |23 and is preferably a contact surface ofElkonite silver.

As seen in Figures 2 (and 17), the contact shaft 45 is a square steelbar which as above described is covered with phenolic insulation moldedin place. Each end of this shaft is drilled at |40a to receive thebearings |40. The shaft itself extends between the side plates y28 and29. The bearings are brass cylinders inserted in holes in the sideplates to which their drilled flanges |4| are secured by screws |42.

When the screws |42 are removed and the two bearings at each end arewithdrawn, the shaft and the entire contact assembly may be removed frombetween the side plates provided of course that the flexible leads havebeen disconnected and also provided that the connection between the link34 and the arm 35 of the contact shaft are separated.

Assembly and operation of the contacts The contact arms 43 (see, forinstance, Figure 3 and 17) are secured to the contact shaft by clampmembers 3| which are held in place by a pair of screws 56 and 51 on eachside of the shaft.

The outside poles are suitably positioned (Figure 17) by the contact armcaps or clamps 5ta while the middle pole arm is held in position by thecap 5|. As is seen more particularly in Figure 3 the clamp or cap 3| isextended to form the shaft actuating arm 35 and is drilled to receivepin 2| ii in the upper end of the main toggle link 34. A movement of theoperating mechanism 3| will raise or lower the pin 2MB, thereforeraising or lowering the shaft actuating arm 35 and so rotate the contactshaft d5 to move the contacts into and/or out of engage ment. f

Asis more clearly seen in Figures 2 (and 17) secured to either or bothends of the steel contact shaft 45, is a steel arm 220 and 22|. Each ofthese arms carries as will be noted, two studs 223 and 224 which areriveted in place.

Secured to one of the studs of each of the members 220 and 22| is acontact opening spring the lower end of which may be attached to studsriveted to the insides of the bracket side plates. These two springs maybias the shaft towards opening position and assure quick opening.

The second of the studs for instance stud 223 on the arm 220 may beutilized to operate auxiliary switches or other devices by means, forinstance, the vertical insulated shaft 230 attached to this stud andpassing through the shelf of the bracket 3|! (Fig. 2).

Thus, for instance, the vertical shaft 230 may operate auxiliary switch234 in any suitable manner for any suitable purpose. The rotation of thecontact shaft 45 towards opening position will through the arm 220 andthe stud 223 force the vertical line 230 downwardly. The vertical link230 is connected by pin 23| to the crank 232 on the shaft 233 ot theswitch 234. The downward motion of the vertical link 230 will result inrotation of the crank 232 and will therefore result in rotation of theshaft 233 and in the consequent operation of the various contacts andother portions of the switch suitably connected to and actuated by shaft233.

Such switch 234 may be used where, for instance, the circuit breaker isto be connected with automatic reclosing circuits when it is open andsuch relay will obviously be reset to its original position when thesolenoid or manual closing mechanism hereinafter described rotates thecontact shaft 45 towards closing position thus raising the insulatedlink 230 and operating the switch.

As has been above pointed out, preferably three contact arms 46 aremounted on this shaft, one for each pole of the circuit breaker as seenin Figure 2. On each side of each arm, there is cemented to the shaftinsulation a bakelite washer |43 which improves the pole to pole andpole to ground insulation.

As will be noted in Figure 2, the inter-pole washers are bevelled andflanged so that the bevelled and flanged portions |44 thereof are spacedapart so that an inter-phase barrier |45 secured to the panel may extendbetween them. The cooperation of these parts makes it impossible for anyflexible conductors of adjacent poles to be drawn together during heavycurrent flow while at the same time any possibility of arcing over isobviated.

In the construction and arrangement of the contacts, the movable maincontact is supported by an operating arm on the contact bar or shaft andis connected to the lower stud by a flexible shunt of suitable size.

Pressure on the main contact is obtained through the use of acompression type coil spring, mounted outside the current path, andconsequently, is unaffected by heating.

The pressure on the arcing contacts is also obtained by the same type ofcompression type coil spring protected from the arc.

The main contacts are protected by the sequence of operation in openingor closing of the device, since the main contacts close after the arcingcontacts and open before them.

Although with the construction herein described, replacement of thecontacts should not be necessary, the arrangement of the movable maincontact lever and the movable arcing contact is such that access to bothstationary and movable parts with a minimum amount of labor is possible.

As hereinafter described, accessibility of the main contacts is suchthat it is necessary only to remove one screw from the arc quencherassembly and lift it 01T manually so as to reach the contacts. Inaddition, as is hereinbefore described, the removal of the two bearings|40 of the main contact shaft and pigtails is suilicient to makeavailable all parts of the contact mechanism for replacement, cleaningor repair.

The individual poles of the circuit breaker are each rigidly mounted ona rigid insulating shaft so as to insure the simultaneous opening andclosing of all contacts. The use of a single trip free mechanism (in themanner hereinafter described,) operating the main contact shaft alsoinsures that all of the poles will operate simultaneously and precludesthe possibility of opening individua1 poles without opening others.

An important feature of the present invention is that the same structuremay be used for single pole or multi-pole operation, that is, as seenfor instance in the structure of Figure 2, the circuit breaker mechanismis so arranged that three poles are simultaneously operated by a singleclosing and tripping mechanism. 'I'he same type of structure may be soarranged as to take one, two or four poles or more.

In massproduction manufacturing processes where tooling and dies andother operations should be so adjusted as to make it possible to obtaindifferent types oi.' products by the use of the same general operations,it is preferred that the standard tools and manufacturing processes bearranged to make circuit breakers having the maximum number of poles tobe generally cxpected in a particular eld. Although four poles or evenmore in certain special instances may be necessary, the usual maximumnumber of poles which may be required in ordinary installations isthree.

Thus, in the ordinary process of manufacture, all of the elements may bemade as shown in Figure 2 to accommodate three pole structures. Wherethe circuit breaker is to be used as a single pole circuit breaker, thenit will be necessary merely to remove the two outer poles shown inFigure 2, leaving only the center pole. That is, the members removedfrom the circuit breaker (or not attached thereto during the process ofmanufacture) will comprise the left and right arc quenchers of Figure 2and the left and right contact assemblies of Figure 2, leaving thecenter arc quencher and the center arc assembly in proper position forsingle pole operation.

Should a two pole circuit breaker be desired, the standard device mayagain be used with the center are quencher and the center contactassembly removed. By this means, the whole development is constructedwith full consideration for standardization and subsequent use inmanufacture and delivery.

By this means also, all circuit breakers whether of the one or two orthree pole variety may be standardized and the only change is theaddition or removal of certain of the poles.

As is hereinafter described, the width of the panel belowthe contactshaft 45 has been reduced as far as possible so that should the threepole circuit breaker of Figure 2 be used as a single pole circuitbreaker, then the only waste assenze space is the marginal portions ofthe upper part of the panel 23 which is relatively no loss at all sincein ordinary practice it is desirable that the mounting panel berectangular.

The same consideration applies where the center pole assembly is removedand the circuit breaker is used as a two pole circuit breaker. The valueand utility of these different variations will further be brought out inconnection with the description of other members of the circuit breakerassembly.

Arc chute, arch horns and blow out In the actual operation of thecontact assemblies herein described. when the contacts are fully closedand the latches vare then tripped, the contact shaft 45 and the contactarm 43 rotate in a counterclockwise direction in the views of Figures 3and 4. As the arm and the contact pivot pins 13 and 33 move away fromthe stationary contacts, the springs 33 and 35 maintain the movingcontacts in engagement with the stationary contacts until in therotation of the contact levers these levers 15 and 33 strike theirrespective stops.

During this movement, the lower end 12 of the contact lever 30 strikesthe part of the contact arm 43 which surrounds the shaft I5. At thispoint in the movement, the main contacts separate while the arcingcontacts arestill engaged. It is thus seen that the circuit through themain contacts is interrupted and all the Jcurrent is transferred to thecircuit of the blow out coil |22 and the arcing contacts. The core |30therefore and its associated pole pieces are highly magnetized inproportion to the current flowing.

As seen in Figures 2, 3, 4 and 5 surrounding, each pole is an arc chute|50 comprising side plates |5| of fiber and supporting between them fiveshorter parallel spaced plates |52 also of nber. The entire group isheld togetherpreferably by rivets |53, |53 making as far as possible arigid assembly. Heferably, the rivets comprise, as seen in Figure 5, acentral metal tube-like arrangement |5I and an outer insulating cylinder|55.

plates IBI.

AsseeninFigures3and4,nea.rthepanel,v

the inside plates |52 are separated by f lber mem bers |53 which preventthe are gases from coming in contact with the panel and which alsocomprise hooks |51 which engage under the hook or lip |33 of thestationary arcing contact member |23 in order to assist in supportingthe arc quencher assembly. Near the front of the arc chute is secured abrass arcing horn |30 which is electrically connected to an angle-clip|3|, being connected thereto by the screw |32 passing through the flange|33 of the arcing horn and a flange of the angle clip.

The metallic clip |3| is secured by the screw |34, and lock washer |35to the bridge 31 of molded insulating material. This metallic clip |3|is electrically connected to the flexible conductor |00 which in turnconnects it to the lower pig-tail terminal ll. At the end of the openingmovement of the arcing contact the tip 31 of the movable arcing contact15 moves under the stationary arcing horn |30 in the manner shown inFigure 4 so that the arc terminal is transferred to the stationaryarcing horn |30 and the current flows through the conductor |00 to thelower terminal block 4l. The current is rst transferred from the maincontacts to the arcing contacts, and, when are arc is then transferredto the stationary The ber side plates are notched at |15. as seen inFigure 1, so that they may embrace the core |30 while their edges restagainst the panel 23.

By this arrangement, any possible impediment to the magnetic fluxesinduced by the core in the pole pieces hereinafter described isobviated.

Ferrous blow out plates or pole pieces |13,

lFigures 1,2 and 5, are secured to the outer s urfaces of the sideplates |5| of the arc chute by means of rivets or other suitableattaching means |11. 'Ihese blow out plates or pole pieces, as seenparticularly in Figure 1, cover a part of the notch |15 in the fiberplates |5| so that when the arc chutes are in position against the panel23 and in proper relation to the contact assembly, the surface of eachend of the core |30 is in contact with a corresponding iron blow outplate or pole piece |13.

Each of the side plates has its back edge |80 (Figure 1) bevelled on theinner side thereof so that it may be slid in position easily past thenotches of the insulated bridge hereinafter de scribed. l 1

The notch |15 around the blow out core |30 (Figure 1) and the lip |33 onthe stationary arcing contact m which engages the hook |51 of the i'iberspacer |53 of the arc chute |50 (Figure v 3) cooperate to position theback end of the arc chute in exact relation to the. panel 23 and to thevarious other portions of the contact assembly.

The front end is supported and locked in place by means of the screw |34passing through the insulating bridge31 and through the angle clip |3|which in turn is affixed by means'of the screw |32 to the stationaryarcing horn |50v which in turn is preferably an integral part of' orsecurely attached to the arcing chute |50.

The front end of the arc chute is therefore securely positioned in placeby means of the screws |34 and |32. -It will be noted that removal ofthe screw |32 will permit the withdrawal of the entire arc chute fromthe contact assembly. That is, when the screw 32 is no Y longer inengagement with the angle clip |3| then (Figure 3.) when the entire arcchute |50 lis slid towards the left, the hook |51 of the fiber spacer|53 may be disengaged by this si/mple horizontal movement from the hook|39 of the arcing contact |23 and as seen in Figure 1, the notch |15 ofthe outer plate I 5| may by the same motion slide out of engagement withthe blow out core |30. The arc chute therefore is so arranged that asimple unscrewing of the screw |32 will permit removal thereof.

It should be noted that the screw |32 is so arranged that it need not becompletely removed but it may be rotated a sunicient number of turns todisengage it from the clip |3| and may remain in the portion |33 of thearcing vhorn |30 during removal of the arc chute. By this simplifiedmeans involving rotation of a single screw, the arc chute may-besecurely mounted in place or quickly removed by a single motion warddirection with the cusp U2 between them rounded. This cusp liesapproximately midway between the stationary arclng horn |23 and thefront arcing horn |80. 'I'he downwardly extending cusps facilitate theentrance of the arc into the slots between the' plates and are soarranged that a relatively small longitudinal length of the arc is rstforced between the plates and so that as the arc is blown upwardly,progressively greater lengths of the arc are forced between the lplates.

able size and shape, spaced and arranged to permit the flow oi' arcgases from the slot |98 (Figure 5) between one pair oi plates to theslot between another. In order to provide a more turbulent condition ofthe arc gases and in order to insure contact of the arc gases with thevarious plates, the holes or perforations |85 of each of the plates arein staggered relation with respect to those in adjacent plates.

Upon opening of the main contacts and formation of the arc between thearcing contacts 14 and |23, the arc is immediately transferred from thearcing tip 14 to the arcing horn |80.

The current flowing through the coil |22 energizes' the magnetcomprising core lli! and ferrous plates |18 producing a flux across thearc space. This ilux forces rthe are upwards towards and into the arcchute i5ll. When the arc reaches 'the lower edges of the arc splittersoi plates l52 it is squeezed or flattened to be forced between the twoouter plates |52c and 452e. Further movement forces the arc between theintermediate plates |52b-l52b further reducing its horizontal Iwidth.

As thearc is pushed further it may enter one ci' the slots |90 or it maybe divided longitudinally in two or more slots. In either case, the arcgases have an opportunity to expand through the holes |55 in the plates|52.

'This provision for permitting the arc gases to expand from slot to slotreduces the back pressure and hence permits the blow out magnet to Thetendency of the ionized gases discharged -irom one slot to enter anotherthrough the perforations |95 permits vparallel arcs to exist oversections of the arc. This causes greater instability and increasedtendency to speed the extinguishingof the arc.

By this means also a large cooling area is provided which furthercontributes to shorten the arcing time. Preferably the arc gases aresumciently cooled and deionized by the arc quencher so that when, in thecase oi' alternating current, the current passes through zero in thecycle immediately following the formation of the arc, the gases will besuiilciently deionized to provide an extremely dimcult path for an arcand thus prevent the re-striking thereof. The arc therefore may bequenched within 1/120 of a second of the formation thereof.

litter-phase barriers ried up so that they are aligned with the topl ofthe panel 23 and may be secured to the panel by suitable angle clips200, Figure 2, and screws 20| passing therethrough;

As will also be seen in Figure l, the interphase barrier |45 extendsbeyond the arc chute both at the top and 'the front. The front lowercomer rests on the insulation bridge 31 while as has been before pointedout, the back end bears against the panel and extends down between theshaft insulation disks Ill-|43.

Lower interphase barriers llllla (Figure 1) are aligned with the upperinterphase barriers and' secured to the panel 22 by screws Illia and|||2a thus preventing any tendency of the flexible leads to approacheach?` other or any current at that point from arching over.

The lower back corner of the upper interphase barrier is supported by astrip of insulating material secured to the panel Just above the top ofthe housing brackets. The lower interphase barriers align with the upperones and are secured to the panel by screws threaded into their edge.

These lower barriers are notched to surround the shaft. They prevent theflexible conductors from being drawn together during fault current.

Operating mechanism (closing and tripping) An extremely importantelement of the present invention and of the combination herein set forthis the operating and tripping mechanism 3| (Fis-z ures 1. 3 and 4). Theelements of this operating and tripping mechanism are more clearly setforth in Figures 6 through 16, inclusive. The entire mechanism 3|itself, however, is contained within the housing 300 (Figure 3) which isa steel box closed on the front, bottom and sides with Ilanges 32 at theupper edges of the sides so that it may be secured by the bolts 33 tothe shelf 30 of the housing bracket assembly. The side walls of thehousing 30|! are pierced for the main stationary pins of the mechanismand the metal around the holes is extruded inwardly and reamed to obtainproper bearing for the pins.

Referring now more specifically to Figures 9 and 10, 13 and 14, the link34 in each of these figures is the member which engages the actuatingarm 35 of the contact shaft 45.

Figure 9 shows the position of each of the members of the operating andtripping mechanism when the circuit breaker is opened. Figures 10 and 13show the position of each of the members when the contacts of thecircuit breaker are closed. Figure 14 shows an intermediate momentaryposition of each of the members at the completion ofthe trippingoperation, and an instant before re-set of the latches.

In the following description of the details of v operation, referencesshould be made as to each member to the drawings of Figures 9, 10, 13,and

14, while also the top view of Figure 6 and the horizontal crosssectional view of Figure 7 will :iid in the understanding of the variousoperaons.

In further aid of the following description. the

thestationary pin 422.

to. Figure 22 shows the closed position corresponding to Figures and 13;Figure 24 shows the open position corresponding to Figure 9; Figure 23shows the position at tripping and immediately before latch re-setting,corresponding to Figure 14; and Figure 25 is a diagrammatic illustrationof the trip-free position in the case of operation of the latches whilethe manual or solenoid closing member is in engagement.

The operating mechanism comprises a plurality of toggles so arrangedthat the knee pins or knuckle pins of each may be supported when thecontacts are closed; but wherein the supports may be removed, permittingthe contacts to open mounted on the xed pivot 404 which is rotatablycarried in the perforations of the metal side Walls ofthe outer casing.

The operating link 400 carries rotatably mounted therein'betwcen theside plates 40| and 402, the knee or knuckle pin 405.

Link 406 comprising also a pair of side plates 401 and 408 and a tieplate 409 for rigidifying purposes is rotatably mounted at one endthereof on the knee or knuckle pin 405.

The link 406 carries at the opposite end thereof the pin 4|0 which isrotatably mounted therein between the side plates 401.-400 thereof. Pin4|0 carries rotatably mounted thereon a lug 4|| providing a means forsecuring one end of the tension spring 4|2 thereto. The opposite end oftension spring 4|2 is secured to a lug 4|3 which is rotatably mounted ona rivet head 4|4 which is carried by the upstanding lug 4|5 of the sideplate 40| of the link 400.

The effect of the tension exerted by spring 4|2 between the points 4|4and 4|0 is to collapse the toggle comprising links `400 and 406 to theposition shown in Figure 9. I

A third link 4 6 comprising a pair of independent side plates isrotatably mounted at one end thereof on the pin 4|0. The opposite end ofthe link' 4|6 is rotatably connected to the pin 4|1 which is carried bythe latch lever A4 8;

The latch lever comprises a pair of side plates 4|9 and 420 with a tieplate 42| therebetween. One end 4of the latch lever is rotatably mountedon the iixed pin 422 so that it is free to rotate thereon.

Pin 4|0 also rotatably supports one end of the connecting link 34, whichextends between-the operating mechanism and the actuating arm of thecontact shaft. This link is a single wide member of phenolic insulation.

An abutment 425 is also rotatably mounted on The abutment ormain latch425 comprises a V-shaped member having a center portion -426 which ispivotally mounted on the pin 422, an abutting or latching portion 421adapted to engage a roller on the pin 405 in the manner hereinafterdescribed, and a release portion 428.

The upper edge of release portion 428 is adapted to lie in engagementwith the under side of tie plate 42| of the latch lever 4|8. so that anymovement downward of the latch lever 4|8 Will result in a clockwiserotation of the said portion 428 of the abutment 425 and will result inmoving the abutting or latching portion 421 thereof out of engagingposition.

vA spring 440 is so arranged as to tend to yieldingly support theabutment member 425 so that the latching portion thereof 421 may alwaysbe in position to engage the roller 405.

Pressure of release portion 428 against the plate 42| of the latch leverlimits the effect of the spring 440 and serves positively to positionlatching portion 421 in predetermined position.

When the link 400 is raised and the knee pin 405 of the toggle formed bythe links 400-400 is therefore raised then since the link 4I8 (by meansof its attachment between pins 4I0 and 4| 1) prevents pin 4|0 fromapproaching closer to the pin 4|4, the only direction in which the link400 may rotate by reason ofthe elevation of the pin 405 is in such adirection that the pin 4|0 moves counterclockwise with respect to pin405.

In this manner, raising of the link 400 in any suitable manner resultsin an extension oi' the tension spring 4|2 (the members then assumingthe position shown in Figs. 9 and 13) and in an increase of forcetending to draw the pins 4|0 and 4 i4 togethery creating a tendency tocollapse the toggle formed by links 406 and 400.

The members are arranged so that when the toggle formed by links 400-408about pin 405 is in such position that the contacts of the circuitbreaker are closed (as for instance in Figure 1Q) the toggle is justunder center, that is .the center of pin 405 does not reach a straight(imaginary) line drawn between the axes of the pins 404 and 4|0 and doesnot pass through such line.

In this way, this toggle is unstable even when set in the closed circuitposition. When therefore, the supporting means herein described isremoved from the toggle it will immediately collapse owing to thetendency oi the tension spring 4|2 to draw the pins 4|0 and 4| 4together.

In the open circuit position and even in the closed circuit position,the pin 4|1 is a stationary one in that it is mounted on the latch lever4|0 one end of which is fixed by its mounting on the pin 422 and theother end of which is'iixed by the engagement of the latching tip 430with the notch 43| of the primary latch 432.

Therefore during the closing operation the lower center of rotation ofthe link 4|6 is xed and for this reason also the pin 410 is to someextent supported by the link 4|6.

This partial support of the pin 4|0 by the link 4|6 results in downwardpressure upon the latch lever 4|8 in closed circuit position of Figures10 and 13 thus resulting in pressure of the latch lever trip 430 uponthe base 433 of the notch 43|.

As the operating link 400 of the toggle 400-L 406 is raised, the roller405 of the toggle comes in contact with the surface 434 'of the abutment425 and moves the same in a clockwise direction (with respect to Figures9 and 10) out of the way so that the knee pin 405 may rise. After thispin has passed the area 434 of the abutment 425 then the spring 440 ofthe abutment pushes the abutment 425 in a counterclockwise direction(with respect to Figures 9 and l0) so that the member 428 of theabutment abuts against the tie plate 42| of the latch lever 4|8 and sothat the abutting portion 421 is swung beneath the knee pin 405 of thetoggle 400- 406 (in the position showninFigures 10 and 13) to supportthe same against the tendency of the tension spring 4I2 to pull the pins4M and 4I0 together and thus collapse the toggle by driving down theknee pin 405. Y

Should the abutting or latching portion 421 o1' the abutment 425 beagain rotated (clockwise

